The present invention relates, in general, to hermetic compressors and, more particularly, to a working-fluid intaking structure for such hermetic compressors designed to directly feed sucked working-fluid to a suction muffler within a hermetic compressor.
FIG. 1 shows the internal construction of a conventional hermetic compressor. As shown in the drawing, the conventional hermetic compressor comprises a hermetic housing 1 consisting of upper and lower casings 1t and lb, with a frame 2 being set within the housing 1. A stator 3 is fixedly mounted to the frame 2. Such a frame 2 is held in the hermetic housing 1 by a spring 2S.
A crankshaft 5 is installed within the housing 1 while passing through the central portion of the frame 2, while a rotor 4 is integrated with the crankshaft 5 into a single structure. The above rotor 4 is electromagnetically rotated along with the crankshaft 5 in cooperation with the stator 3. An eccentric pin 5b is provided on the upper end of the crankshaft 5 while being eccentric from the rotating axis of the crankshaft 5. The construction of the eccentric pin 5b will be described in more detail later herein.
On the other hand, a cylinder 6, having a compression chamber 6xe2x80x2, is integrated with the frame 2 into a single structure, with a piston 7 being set in the compression chamber 6xe2x80x2 of the cylinder 6. The above piston 7 is connected to the eccentric pin 5b of the crankshaft 5 through a connecting rod 8.
A suction muffler 9 is installed within the hermetic housing I while communicating with the compression chamber 6xe2x80x2 of the cylinder 6, with a suction pipe 10 being directly coupled to the suction muffler 9 through a coupling cap 11. The object of the above suction muffler 9 is to reduce operational noises of the working-fluid, sucked from the outside of the compressor into the compressor housing 1, prior to feeding the working-fluid to the compression chamber 6xe2x80x2 of the cylinder 6. The coupling structure between the coupling cap 11 and the suction muffler 9 is shown in detail in FIG. 2. As shown in the drawing, the coupling cap 11, having a predetermined shape, is inserted into the suction port 9xe2x80x2 of the suction muffler 9, while the suction pipe 10 is coupled to the coupling cap 11 using a spring 12.
A stop projection 11j is formed on the upper end portion of the above coupling cap 11, and so the coupling cap 11 is caught by the interior surface of the suction muffler 9 at the stop projection 11j when the coupling cap 11 is fully inserted into the suction port 9xe2x80x2 of the suction muffler 9. A limit projection 11s is formed at the lower end portion of the coupling cap 11 and limits the insertion of the cap 11 into the suction port 9xe2x80x2 of the muffler 9. The lower end portion of the coupling cap 11 is gradually and linearly enlarged in diameter in a direction from the limit projection 11s to the distal end.
On the other hand, the spring 12 is fully inserted into the coupling cap 11 at one end thereof and is fitted over the upper end of the suction pipe 10 at the other end thereof. Such a spring 12 normally biases the cap 11 toward the suction muffler 9, thus elastically holding the cap 11 relative to the suction muffler 9 while absorbing and releasing operational vibration of the compressor.
In the drawings, the reference numeral 13 denotes an exhaust muffler that is used for reducing operational noises of compressed refrigerant exhausted from the compression chamber 6xe2x80x2, and the reference character L denotes oil used for lubricating and cooling the parts of the compressor.
In an operation of the above conventional compressor, working-fluid is introduced into the compression chamber 6xe2x80x2 of the cylinder 6 as follows. That is, the working-fluid orderly passes through the suction pipe 10 and the coupling cap 11 prior to being introduced into the suction muffler 9. The working-fluid is reduced in operational noises while passing through the suction muffler 9 and flows into the compression chamber 6xe2x80x2 of the cylinder 6.
However, the above conventional hermetic compressor is problematic as follows.
That is, the coupling cap 11 is elastically inserted into and held in the suction port 9xe2x80x2 of the suction muffler 9 due to its own elasticity, and so it is necessary for both the coupling cap 11 and the suction port 9xe2x80x2 to have precise dimensions. However, the size of the coupling cap 11 may be larger than that of the suction port 9xe2x80x2 in an effort to accomplish a desired machining allowance. In this case, it is very difficult to assemble the coupling cap 11 with the suction port 9xe2x80x2 of the suction muffler 9.
On the other hand, when the size of the coupling cap 11 is exceedingly smaller that of the suction port 9xe2x80x2, the coupling cap 11 may be undesirably moved within the suction port 9xe2x80x2 during an operation of the compressor. This finally undesirably induces vibration to the parts that are operated in conjunction with the coupling cap 11, thus reducing the operational reliability of the compressor. Such an exceedingly small cap 11 also forms undesirable metal powder within the suction port 9xe2x80x2, the metal powder being formed by a frictional movement of the cap 11 relative to the suction port 9xe2x80x2.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a working-fluid intaking structure for hermetic compressors, which is designed to more firmly and stably connect the suction pipe to the suction muffler.
Another object of the present invention is to provide a working-fluid intaking structure for hermetic compressors, which allows the suction pipe to be more easily and simply connected to the suction muffler.
In order to accomplish the above object, the present invention provides a working-fluid intaking structure for hermetic compressors, comprising a working-fluid suction means set in a hermetic compressor while extending through the hermetic housing of the compressor, a suction muffler set in the hermetic housing and used for reducing operational noises of sucked working-fluid fed from the working-fluid suction means prior to feeding the working-fluid to a working-fluid compression part of the compressor, a coupling cap inserted into the suction muffler while being elastically held at a desired position of the suction muffler by an elastic member allowing the working-fluid suction means to communicate with the suction muffler; and a plurality of pressure projections formed on the coupling cap and used for firmly setting the coupling cap on the suction muffler.
In the working-fluid intaking structure, the pressure projections may be formed on at least one of the external and internal surfaces of the coupling cap so as to be brought into close contact with the internal surface of a suction port of the suction muffler and with the external surface of the elastic member. It is also preferable to axially form the pressure projections on the coupling cap.
In accordance with the working-fluid intaking structure for hermetic compressors of this invention, it is possible to easily and firmly set the coupling cap at a desired position of the suction muffler, with the coupling cap be used for connecting a suction pipe to the suction muffler.